Frank j



(No Model.)

'P. J. SPRAGUE.

ELEGTRO DYNAMIC MOTOR. No. 321,147. Patented June 30, 1885.

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UNITED STATES PATENT Orricrt.

FRANK J. SPRAGUE, OF NEV YORK, N. Y., ASSIGNOR TO THE SPRAGUE ELECTRICRAILWVAY AND MOTOR COMPANY.

ELECTRO-DYNAMIC MOTOR.

SPECIFICATION forming part of Letters Patent No 321,147, dated June 30,1885.

(No model.)

To aZZ whom it may concern:

Be it known that I, FRANK J. SPRAGUE, of New York, in the county andState of New York, have invented a certain new and useful Improvement inElectro-Dynamic Motors, of which the following is a specification.

In the operation of a shunt-wound electrodynamic motor on a circuit ofconstant difference of potential it is desirable when the motor isstarted to have a strong field-magnet and little current in thearmature-circuit, and then to gradually increase the difference ofpotential at the armature-circuit terminals, and then to graduallyweaken the field-magnet, so as to progressively increase the speed ofthe motor and when the motor is running it is desirable, in order tochange the speed or power, or both, of the motor, or to maintain thespeed constant or practically constant under varying loads, to changethe strength of the field-magnet without affecting the armaturecircuit,while in other cases, as in some circumstances which arise in theoperation of moving motors on electric railways, it is desirable to varythe armature-current without affecting the field magnet strength.

To enable these various regulations to be readily performed is theobject of the present invention.

In accomplishing this obj ectI provide means independent of each otherfor regulating the armature-current and the field-magnet strength,respectively. Thearmatureregulatingmeans is preferably an adjustableresistance in thearmaturecircuit, and the regulator for the field-magnetmay be an adjustable resistance or other known device or constructionfor this purposesuch, for instance, as those set forth in my priorapplications for patents.

My invention is illustrated in the accompanying drawings, in whichFigure 1 is a diagram of a motor provided with regulating devicesembodying my invention, and Fig. 2 a similar diagram showing a diiferentfieldmagnet regulator.

1 2 are main conductors of a supplying-circuit, preferably a circuit ofconstant difierence of potential, with which I prefer to use myinvention. 3 4 is the armature-circuit, and 5 6 the field-circuit of ashunt-wound electrodynamic motor A. In the field-circuit 5 6 is anadjustable resistance, B, Fig. 1, and in the armature-circuit 3 4 is anadjustable resistance, C. It will be seen that each of these resistancesis controllable independently of the other. Thus to increase thestrength of the field-magnet a portion of the resistance Bis cut out ofcircuit, and to decrease its strength more of the resistance B is placedin circuit. Thus the regulation of the field-magnet is performed withoutaffecting the armature-circuit. The current in the armature is similarlycontrolled without affecting the field-magnet by the adjustment of theresistance 0. The regulating means for the two circuits may include,also, a circuit-reverse for each circuit D or D, whereby the current ineither circuit is reversed without affecting the other circuit.

The field-magnet regulator shown in Fig. 2 consists of a circularcommutator, E, to the blocks of which are made connections 7 7, from thebights of sections into which the fieldmagnet coils are divided, suchsections being connected together into a continuous closed circuit, andeach section being wound from end to end of the core, although in thedrawings, for convenience of illustration, the sections are placed sideby side on the cores. The supplying terminals of the field-coils areconnected with the two pivoted arms a a on the commutator E, and bymoving said arms upon the commutator the current is reversed in more orless of the field-coil sections, whereby the strength of thefield-magnet is varied independently of the armature. As this apparatusalso may effect the reversal of the field magnetism, the currentreverserD is here dispensed with. v

In the armature-circuit is an adjustable resistance, O, andcircuit-reverser D, whereby the armaturecircuit is independentlyrcgulated, as before.

The reversing-switches may be used to make and break the circuits, oradditional circuitcontrolling switches may be provided.

The arrow-heads in the drawings show the direction of current in thecircuits.

It is evident that my invention is applicable to the armature andmain-field circuits of that class of shunt-wound motors having diiferen-1C0 tial coils in series with the armature, although it is set forthwith relation to a simple shuntwound machine.

\Vhat I claim is- 1.. A shunt-wound eleotro-dynamic motor provided withmeans for varying its armaturecurrent and independent means for varyingthe strength of its field-magnet, substantially as set forth.

2. A shunt-Wound electro-dynamic motor provided with means for varyingthe strength of its field-magnet and with an adjustable resistance inits armature-circuit, substantially as set forth.

3. The combination, with a shunt-Wound electro-dynamic motor, ofindependently-adjustable resistances in its armature and fieldcircuits,substantially as set forth.

4:. The col'nbination, with a shunt-wound electro-dynamic motor, of acircuit-reverser, and an adj list-able resistance in itsarmaturecircuit, and means for varying and reversing its fieldmagnetism, substantially as set forth.

The combination, with a shunt-wound electro-dynamic motor, of a circuit'reverser, and an adjustable resistance in its armaturecirouit, and acircuitreverser and an adjustable rcsistance in its field-circuit,substantially as set forth.

This specification signed and witnessed this 24th day of February, 1885.

FRANK J. SPRAGUE.

WVitnesses:

A. W. RIDDLE, E. O. ROWLAND.

